Within the magazine, was a machine, constructed to run any proposed length of time under twelve hours. When it had run out its time, it unpinioned a strong lock resembling a gun-lock, which gave fire to the powder. This apparatus was so pinioned, that it could not possibly move, till, by casting off the magazine from the vessel, it was set in motion.
This skilful operator could swim so low on the surface of the water, as to approach very near a ship in the night without fear of discovery, and might, if he chose, approach the stem or stern above water, with very little danger. He could sink very quickly, keep at any depth he pleased, and row a great distance in any direction he desired, without coming to the surface; and, when he rose to the surface, he could soon obtain a fresh supply of air; when, if necessary, he might descend again and pursue his course. The projector found some time and attention to be requisite for the gradual instruction of this operator, and, after various attempts, he found one, on whom he thought he could depend. He sent this man from New York to a 50 gun ship, lying not far from Governor's island. He went under the ship, and attempted to fix the wood screw in her bottom, but struck, as he supposed, a bar of iron, which passes from the rudder's hinge, and is spiked under the ship's quarter. Had he removed a few inches, which he might have done without rowing, the projector has no doubt but he might have found wood, where he might have fixed the screw; or if the ship were sheathed with copper, he might easily have pierced it. But, not being well skilled in the management of the vessel, in attempting to row to another place, he lost the ship. After seeking her in vain some time, he rowed to some distance, and rose to the surface of the water, but found day light had advanced so far, that he durst not renew the attempt. He says, he could easily have fastened the magazine under the stern of the ship above the water, as he rowed up to the stern, and touched it before he descended. Had he fixed it there, the explosion of 150 lbs of gunpowder (the quantity contained in the magazine) must have been fatal to the ship. In his return from the ship to New York, he passed near Governor's island, and thought he was discovered by the enemy on the island. Being in haste to avoid the danger he feared, he cast off the magazine, as he imagined it retarded him in the swell, which was very considerable. After the magazine had been cast off an hour, the time the internal apparatus was set to run, it blew up with great violence.
Mr. Griswold gives an account of an attempt to destroy a ship of war; and having received his information from Mr. Lee, one of the adventurers, we have thought proper to introduce it from that source.
"It was in the month of August, 1776, when Admiral Howe lay with a formidable British fleet in New York bay, a little above the narrows, and a numerous British force upon Staten Island, commanded by General Howe, threatened annihilation to the troops under Washington, that Mr. Bushnel requested General Parsons, of the American army, to furnish him with two or three men to learn the navigation of his new machine, with the view of destroying some of the enemy's shipping.
"General Parsons immediately sent for Lee, then a sergeant, and two others, who had offered their services to go on board a fire ship; and on Bushnel's request being made known to them, they enlisted themselves under him for this novel piece of service. The party went up into Long Island sound with the machine, and made various experiments with it in the different harbours along shore; and after having become pretty thoroughly acquainted with the mode of navigating it, they returned through the sound; but, during their absence, the enemy had got possession of Long Island and Governor's Island. They, therefore, had the machine conveyed by land across from New Rochelle to the Hudson river, and afterwards arrived with it at New York.
"The British fleet now lay to the north of Staten Island, with a large number of transports, and were the objects against which this new mode of warfare was destined to act. The first serene night was fixed upon for the execution of this perilous enterprize, and sergeant Lee was to be the engineer. After a lapse of a few days, a favourable night arrived, and, at 11 o'clock, a party embarked in two or three whale boats, with Bushnel's machine in tow. They rowed down as near the fleet as they dared, when sergeant Lee entered the machine, was cast off, and the boats returned.
"Lee now found the ebb tide rather too strong, and before he was aware, had drifted him down past the men of war. He, however, immediately got the machine about, and by hard labour at the crank for the space of five glasses by the ship's bells, two and a half hours, he arrived under the stern of one of the ships at about slack water. Day had now dawned, and by the light of the moon he could see the people on board, and hear their conversation. This was the moment for diving: he accordingly closed up over head, let in water, and descended under the ship's bottom. He now applied the screw, and did all in his power to make it enter; but owing probably in part to the ship's copper, and the want of an adequate pressure, to enable the screw to get a hold on the bottom, his attempts all failed. At each essay, the machine rebounded from the ship's bottom, not having sufficient power to resist the impulse thus given to it. He next paddled along to a different part of her bottom, but, in this manœuvre, he made a deviation, and instantly rose to the water's surface on the east side of the ship, exposed to the increasing light of the morning, and in imminent hazard of being discovered. He immediately made another descent, with a view of making one more trial; but the fast approach of day, which would expose him to the enemy's boats, and render his escape difficult, if not impossible, deterred him; and he concluded the best generalship would be, to commence an immediate retreat. He now had before him a distance of more than four miles to traverse, but the tide was favourable. At Governor's island, great danger awaited him; for his compass having got out of order, he was under the necessity of looking out from the top of the machine very frequently, to ascertain its course, and at first made a very irregular zigzag track. The soldiers at Governor's island espied the machine, and curiosity drew several hundreds upon the parapet to watch its motions. At last a party came down to the beach, shoved off a barge, and rowed towards it. At that moment, sergeant Lee thought he saw his certain destruction, and as the last act of defence, let go the magazine, expecting they would seize that likewise, and thus all would be blown to atoms together. Providence, however, otherwise directed it: the enemy, after approaching within 50 or 60 yards of the machine, and seeing the magazine detached, began to suspect a yankee trick, took alarm, and returned to the island. Approaching the city, he soon made a signal; the boats came to him, and brought him safe and sound to the shore. The magazine, in the mean time, had drifted past Governor's island into the East river, where it exploded with tremendous violence, throwing large columns of water, and pieces of wood that composed it, high into the air. General Putnam, with many other officers, stood on the shore, spectators of this explosion.
"In a few days, the American army evacuated New York, and the machine was taken up the North river. Another attempt was afterwards made by Lee, upon a frigate that lay opposite Bloomingsdale. His object now was to fasten the magazine to the stern of the ship, close at the water's edge. But while attempting this, the watch discovered him, raised an alarm, and compelled him to abandon his enterprize. He then endeavoured to get under the frigate's bottom; but in this he failed, having descended too deep. This terminated his experiments."
With regard to diving bells, several machines, for the purpose of descending under water, &c. have been invented. Some experiments have been made by the French with similar contrivances, without any adequate result; and the difficulty of carrying them into execution, in real practice, will prevent their introduction.
Dr. Caustic, (Terrible Tractoration, p. 65), in a note, in reference to Bushnel's invention, observes, that if you consult the Transactions of the American Philosophical Society, "you will see what Mr. D. Bushnel, of Connecticut, has done, and had like to have done, by virtue of submarine explosions. You will find, that several English ships have been put in jeopardy, and one schooner actually blown up and demolished by Mr. Bushnel's submarine explosions."[33]